From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:60152) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UeobT-0004HG-Lv for qemu-devel@nongnu.org; Tue, 21 May 2013 11:36:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UeobL-0003BU-Nw for qemu-devel@nongnu.org; Tue, 21 May 2013 11:35:55 -0400 Received: from mail-ee0-f45.google.com ([74.125.83.45]:49574) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UeobL-0003B9-6U for qemu-devel@nongnu.org; Tue, 21 May 2013 11:35:47 -0400 Received: by mail-ee0-f45.google.com with SMTP id l10so493457eei.18 for ; Tue, 21 May 2013 08:35:45 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <519B9449.8000405@redhat.com> Date: Tue, 21 May 2013 17:35:37 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1368628476-19622-1-git-send-email-stefanha@redhat.com> <1368628476-19622-3-git-send-email-stefanha@redhat.com> <519A095D.4070808@redhat.com> <20130521133428.GA6631@stefanha-thinkpad.muc.redhat.com> <519B8EBD.6030006@redhat.com> <24E144B8C0207547AD09C467A8259F7558598818@lisa.maurer-it.com> In-Reply-To: <24E144B8C0207547AD09C467A8259F7558598818@lisa.maurer-it.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 2/8] block: add basic backup support to block driver List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Dietmar Maurer Cc: Kevin Wolf , Fam Zheng , Stefan Hajnoczi , "qemu-devel@nongnu.org" , "imain@redhat.com" , Stefan Hajnoczi , "xiawenc@linux.vnet.ibm.com" Il 21/05/2013 17:25, Dietmar Maurer ha scritto: >> Hmm, right. But do we need the bitmap at all? We can just use >> > bdrv_is_allocated like bdrv_co_do_readv does. > If a write occur, we read and backup that cluster immediately (out of order). So > I am quite sure we need the bitmap. This is the same as how copy-on-read happens during image streaming, and it doesn't use a bitmap. Paolo